The possible long-term renoprotective effects of treatment with thiazides, either as monotherapy or associated with renin-angiotensin suppressors, have not been assessed. We investigated the effect of hydrochlorothiazide (H), alone or combined with losartan (L), in the 5/6 renal ablation model (Nx). Adult male Munich-Wistar rats underwent Nx, remaining untreated for 1 month. At this time, functional and morphologic studies were performed in 21 rats (Group Nx_pre). The remaining rats were distributed among Groups: Nx, no treatment, Nx+L, receiving L, 50 mg/Kg/day in the drinking water, Nx+H, receiving H, 6 mg/Kg/day in drinking water, and Nx+L+H, receiving both L and H as described. At 30 days of treatment, systemic and glomerular pressures were markedly elevated in Group Nx. Both H and L attenuated hypertension, whereas combined L+H treatment completely normalized both pressures. Eight months after Nx, mortality approached 70% in untreated rats, whereas severe albuminuria, hypertension, glomerulosclerosis and interstitial expansion were observed. H and L attenuated, but did not prevent, mortality, hypertension, and renal injury. Combined L+H treatment completely prevented mortality, normalized albuminuria and blood pressure, and arrested renal injury at levels found 1 month after ablation, despite the unusually long period of observation. Combined L+H treatment may represent an effective therapeutic alternative to prevent progression of chronic nephropathies.